Circuit Description
The fuel level sensor measures fuel level changes within the fuel tank and changes resistance based on fuel level. The powertrain control module (PCM) monitors changes in the resistance of the sensor to determine fuel level. When the fuel tank is full, the sensor resistance is high, and the PCM senses high signal voltage. When the fuel tank is empty, the sensor resistance is low, and the PCM senses a low signal voltage. The PCM uses inputs from the fuel level sensor to calculate the total fuel remaining in the fuel tank. This information is then sent to the Instrument via the Class 2 serial data circuit and the powertrain interface module (PIM). When the PCM senses a signal voltage lower than the normal operating range of the sensor the DTC is set.
This diagnostic tests for a stuck fuel level sensor signal. The PCM sets this DTC if the fuel level sensor signal appears to be stuck based on a lack of signal variation expected during normal operation.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The change in fuel volume is less than 0.75 gallons (3 liters) over an accumulated distance of 105 miles (169 km).
Action Taken When the DTC Sets
| • | The instrument multifunction display (MFD) displays the LOW FUEL message. |
| • | The fuel gage defaults to empty |
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails |
| • | The Check Powertrain malfunction indicator lamp (MIL) will not be activated. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records |
| • | The MFD in the instrument cluster will display a message at key-on and key-off. |
Conditions for Clearing the DTC
| • | A Last Test Failed (current DTC), clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | The PCM receives the clear code command from the scan tool. |
Diagnostic Aids
| • | Use the Freeze Frame/Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data may help in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also help in determining the number of ignition cycles that the diagnostic test reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, including those for RPM, for engine load, for vehicle speed, for temperature, and for others. This will isolate at what point the DTC failed. |
| • | Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Did you find and correct the condition? | -- | Go to Step 4 | Go to Step 3 | ||||
3 | Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement in Engine Controls - 5.7L. Did you complete the replacement? | -- | Go to Step 4 | -- | ||||
4 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||
